1. Field of the Invention
The present invention relates to a routing information mapping device in a network.
2. Description of the Related Art
The standardization of MPLS (Multi-Protocol Label Switching) is currently promoted in an Internet standardization group called IEFT (Internet Engineering Task Force). MPLS is a technology to integrate a connection type network, such as an ATM (Asynchronous Transfer Mode), a frame relay, etc., and an IP (Internet Protocol) network, which is one of the most focussed on technologies in the Internet world.
Historically, MPLS has a close relationship with ATM. The present backbone network of the Internet service provider (ISP) is normally composed of ATM switching equipment and an edge device in an ATM network (edge device between an IP network and an ATM network), that is, a backbone network is a mesh type network, which is operated by manually establishing a PVC (Permanent Virtual Circuit) connection and by manually setting a table for indicating pairs of a PVC and a destination IP address in the network.
In these situations, MPLS for automatically establishing connections has been proposed using the address of an IP packet by providing the ATM switching equipment with a router function and by developing a unique connection establishment protocol that operates on an IP network.
Currently, a traffic engineering system for enabling the sophisticated operation of an MPLS network is discussed as a key application in IETF. The central topic under discussion is the load balancing of traffic in the network.
In order to balance the load, a technology for establishing a plurality of routes between one entrance edge device (entrance device from an IP network to an MPLS network) and one exit edge device (exit device from an MPLS network to an IP network) within an MPLS network is indispensable. This technology is called explicit routing. In order to implement explicit routing, two protocols are currently proposed. One is RSVP LSP-tunneling obtained by extending RSVP (ReSource reservation Protocol), which is the signaling protocol of IETF, and the other is CR-LDP obtained by extending LDP (Label Distribution Protocol), which is the original protocol of MPLS. These protocols establish a connection between an arbitrary entrance edge device and a designated exit edge device.
For more information about RSVP, see RFC2205, Resource Reservation Protocol (RSVP)—Version 1 Functional Specification, which is available at ftp://ftp.isi.edu/-notes/rfc2205.text).
However, it is only protocols that are standardized in IETF and the following problems are not addressed.    (1) How can the entrance edge device detect the IP address of an exit edge device?    (2) How can the IP address be related to the established connection?
Therefore, in reality, automatic load balancing is not possible unless the problems described above are solved.
In the present invention, attention is particularly focussed on an IP routing protocol.
Strictly speaking, the flow of an IP packet is defined by the following set of parameters.                {        destination address prefix,        destination port,        source address,        source port,        protocol ID        }In load balancing of MPLS, IP packets are handled in bundle of flows larger than that of flows called FEC (Forward Equivalent Class) flows obtained by arbitrarily combining the parameters of a flow. A specific example of FEC is as follows.            FEC{    Destination address prefix,    Source address    }Load balancing can be implemented by distributing this FEC to a plurality of routes. Although a connection protocol provides a plurality of routes, that is, a plurality of connections, there is no method for relating this FED to the connection. In other words, as long as a mapping method among an FEC and a connection is not established, an automatic load balancing cannot be implemented.
Currently, each vender developing an MPLS router adopts a method for manually generating a mapping table. In a manual setting, the load can be balanced only between two determined points. A great improvement of network performance cannot be expected from such a degree of load balancing.